Levothyroxine sodium is widely used in the treatment and/or prophylaxis of thyroid hormone disorders. Levothyroxine sodium is presently commercially available under the trademark Eltroxin™ in the form of 50 μg and 100 μg tablets. These tablets contain levothyroxine sodium, lactose, magnesium stearate, acacia powder, sodium citrate and maize starch. Whilst levothyroxine sodium is relatively stable in pure form, pharmaceutical formulations containing levothyroxine sodium exhibit a relatively short shelf life, particularly under conditions of high light, heat, air and humidity (see “Kinetics of Degradation of Levothyroxin Sodium in Aqueous solution and in Solid State”, Chong Min Won, Pharmaceutical Research, Vol. 9, No 1, (1992), 131-137). The present Invention is therefore directed at providing a stable solid dosage form of levothyroxine sodium. It is also desired that the solid dosage form disintegrates rapidly, thereby ensuring rapid release of the active ingredient, and is aesthetically acceptable and palatable to the patient.